The present disclosure relates to systems and methods for stabilizing bone structures. More particularly, it relates to systems and methods for stabilizing, and restoring the height of, a bone structure, such as a vertebral body.
Surgical intervention of damaged or compromised bone sites has proven highly beneficial for patients, for example patients with back pain associated with vertebral damage.
Bones of the human skeletal system include mineralized tissue that can be generally categorized into two morphological groups: “cortical” bone and “cancellous” bone. Outer walls of all bones are composed of cortical bone, which is a dense, compact bone structure characterized by a microscopic porosity. Cancellous or “trabecular” bone forms the interior structure of bones. Cancellous bone is composed of a lattice of interconnected slender rods and plates known by the term “trabeculae”.
During certain bone-related procedures, cancellous bone is supplemented by an injection of a palliative (or curative) material employed to stabilize the trabeculae. For example, superior and inferior vertebrae in the spine can be beneficially stabilized by the injection of an appropriate, curable material (e.g., PMMA or other bone cement or bone curable material). In other procedures, percutaneous injection of stabilization material into vertebral compression fractures, by, for example, transpedicular or parapedicular approaches, has proven beneficial in relieving pain and stabilizing damaged bone sites. Such techniques are commonly referred to as vertebroplasty.
A conventional vertebroplasty technique for delivering the bone stabilizing material entails placing a cannula with an internal stylet into the targeted delivery site. The cannula and stylet are used in conjunction to pierce the cutaneous layers of a patient above the hard tissue to be supplemented, then to penetrate the hard cortical bone of the vertebra, and finally to traverse into the softer, cancellous bone underlying the cortical bone. Once positioned in the cancellous bone, the stylet is removed, leaving the cannula in the appropriate position for delivery of curable material that in turn reinforces and solidifies the target site.
In some instances, an effectiveness of the procedure can be enhanced by forming a cavity or void within the cancellous bone, and then depositing the curable material in the cavity. For example, a balloon or other expandable device can be initially deployed and then expanded. This action, in turn, compresses cancellous bone to form a cavity, and may also cause a “height” of the bone to increase. As a point of reference, vertebroplasty is a common treatment for a fractured vertebral body, and the height of a fractured vertebral body is oftentimes significantly less than a native or natural height. It has been postulated that the height of a fractured vertebral body can be restored or elevated to a near-normal state when subjected to internal expansion via a balloon or other expandable member. The mechanics of height restoration in conjunction with vertebroplasty stabilization is currently unclear at best. For example, conventional techniques employ a bipedicular approach in which two balloons are inserted into the vertebral body and inflated, resulting in an increase in height (and the cavity or cavities described above). The sequence of subsequent deflation and delivery of curable material is not well documented.
In light of the above, there exists a need in the medical device field for improved systems and methods for restoring the height of, and stabilizing, a fractured vertebral body or other bone structure.